hmm... seems the problem is caused by the way irssi was compiled, because when I tried one of the other scripts from <a href='http://irssi.org/scripts/' target='_blank'>http://irssi.org/scripts/</a> I got the exact same error message.

This <a href='http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=224930' target='_blank'>http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=224930</a> seems to be related to the same bug. You can use the same work around to get it to work on FREESCO.

Create these two symlinks by running below two commands in a FREESCO command window: